This invention relates generally to medical needles for delivery and extraction of fluid and, more particularly, to such medical needles having a closed tip.
Needles for delivery to, and extraction of fluid, from a body commonly have a hollow shaft that terminates in a pointed open end. Such needles are typically sized to suit particular applications. In dialysis treatments, blood is drawn from the patient, processed through a dialysis machine, and then the processed blood is injected back into the patient. Typically, an arteriovenus shunt, connecting an artery and a vein, is placed in the body, to provide spaced locations to facilitate blood transfer. Two opened-ended needles are used, a first needle to withdraw blood from the shunt, and a second needle to deliver the processed blood back into the shunt. Since the blood is transferred under pressure, these needles must be adequately sized to handle the flow of blood required. As a result, needles currently used in dialysis treatment commonly have a large opening at the distal end of the needle to accommodate the blood flow.
Although such open-end needles are generally effective for fluid transfer, shortfalls exist. For example, such needles can remove tissue when used (i.e., coring tissue), which, in dialysis treatment, can create problems with clotting and can inhibit the life of the shunt. Also, during treatment, cored tissue can hinder the flow of blood through the needle. Moreover, at the point of insertion, current needles commonly create circular penetration marks on the patient, which can impede healing. These shortfalls are not limited to needles used in dialysis treatment, but can also found in various other medical needles used for fluid delivery and extraction.
It should, therefore, be appreciated that there exists a need for a needle configured to facilitate fluid flow while minimizing tissue damage from penetration. The present invention fulfills this need and others.